Protective hoods for the protection of lenses are known in many different designs, especially for military vehicles. As a rule, these have one or more doorlike swiveling flaps for closing the sight opening of the lens, as is described for example in DE 10 2008 039 512 A1. For opening and closing, these flaps are pivoted through a relatively large angle range from a position closing the sight opening to a position adjacent to the outside of the protective hood. Since the protective hoods are usually rectangular in shape and the pivot axis is situated in a corner, the pivot angle is often 270 degrees. The swivel range is thus very large and a lot of room is needed for the swiveling of the flap next to the protective hood. Since this room is generally not available in all placements of the optical device, the optical device must generally first be turned into a defined azimuth position for the opening and closing of the flap, before the sight opening can be closed. This leads to long closure times, so that after the command for a closure has been given there would still be a relatively long time before the closing flap has been shut. During this time, the lens being protected can get damaged, e.g., by a ballistic projectile or a blinding laser device.